Puffer interrupter operating mechanism with magnetic assist and arcless and switchless coil cut-in

ABSTRACT

One end of a helical winding is connected to the movable contact of a puffer type interrupter. The helical winding is slidably connected to a short-circuited ring and the winding or the ring is connected to the puffer interrupter cylinder. A separate operating mechanism connected to the cylinder and the movable contact moves the puffer interrupter contacts open and, at the same time, causes the helical coil to move relative to the shortcircuited ring to cause the coil to carry current, and to create a force of repulsion between the ring and the coil which assists the operating mechanism in operating the contacts to their open position.

United States Patent McConnell PUFFER INTERRUPTER OPERATING MECHANISM WITH MAGNETIC ASSIST AND ARCLESS AND SWITCI-ILESS COIL CUT-IN Inventor: LorneD. McConnell, Chalfont, Pa.

I-T-E Imperial Corporation, Spring House, Pa.

Filed: July 17, 1974 Appl. No.: 489,181

Assignee:

References Cited UNITED STATES PATENTS 3/1973 Yoshioka 200/148 A 7/1973 Yoshioka 200/148 A Primary Examiner-Robert S. Macon Atlorney. Agent, or Firm-Ostrolenk, Faber. Gerb & Soffcn [57] ABSTRACT One end of a helical winding is connected to the movable contact of a puffer type interrupter. The helical winding is slidably connected to a short-circuited ring and the winding or the ring is connected to the puffer interrupter cylinder. A separate operating mechanism connected to the cylinder and the movable contact moves the puffer interrupter contacts open and, at the same time, causes the helical coil to move relative to the short-circuited ring to cause the coil to carry current, and to create a force of repulsion between the ring and the coil which assists the operating mechanism in operating the contacts to their open position.

13 Claims, 11 Drawing Figures PATENTED M152 1975 wv k TmQQ TN W N ww PUFFER INTERRUPTER OPERATING MECHANISM WITH MAGNETIC ASSIST AND ARCLESS AND SWITCHLESS COIL CUT-IN BACKGROUND OF THE INVENTION This invention relates to circuit interrupters, and more specifically relates to a novel auxiliary force producing system for assisting a primary operating mechanism to move the contacts of an interrupter to their opened position. The auxiliary force producing mechanism of the invention uses the repulsion forces between two relatively movable windings which each carry current, and which create magnetic forces tending to move one of the windings and thus a contact to which it is connected but the coils are inserted into the circuit without arcing.

The use of an electromagnetic force which is developed by the current through an interrupter in order to assist external operating forces to open the contacts is well known. Devices of this type which are used in connection with SF 6 gas puffer type interrupters are shown in US. Pat. Nos. 3,531,608 to E. Bateman; 3,549,842 to W. H. Fischer; 3,551,623 to R. G. Colclaser; 3,551,624 to W. H. Fischer; 3,551,625 to W. H. Fischer and 3,551,626 to S. A. Milianowicz. The above patents propose a variety of coil configurations where repulsion or attraction forces between two discrete coils, or some combination of the two forces, is used to assist external contact operating forces. These coils have also been used in connection with radially disposed but axially displaced short-circuiting rings for the above purpose.

All previous known arrangements always employ means for cutting in one or more discrete multi-turn coils, where the cut-in device will consist of a separate mechanically operated arcing switch or some arrangement in which arc currents are transferred to the coil circuit by gas blast action.

Both mechanical and gas blast arcing switches of this type are disadvantageous in that they are costly and complicate the mechanical assembly of the interrupter. The devices also adversely affect the interrupter operation since they increase the erosion of the contact parts and increase 1 R losses under normal current carrying conditions. Moreover, considerable time is required to effect the cut-in of a significant finite value of inductance of a multi-turn coil and the number of turns which can be employed is limited in order to limit the amount of inductance which is inserted into the circuit.

BRIEF DESCRIPTION OF THE PRESENT INVENTION In accordance with the present invention, a novel magnetic assist coil is provided in the form of a helix which is fixed on either the moving or fixed member of the interrupter. One end of the coil is then connected to the movable contact by the normal transfer contacts which are required to carry current from the movable portion of the interrupter to its fixed terminal. The helical coil then makes sliding contact with a relatively movable and concentric short-circuited winding, and the short-circuited winding and spiral winding move relative to one another as the movable contact of the interrupter is moved. As the interrupter begins its opening stroke, the sliding contact between the spiral winding and short-circuited winding moves so that turns of the spiral winding are sequentially connected between the movable contact and its terminal. The sliding contact consists of a multiple contact finger assembly on the periphery of the short-circuited winding which makes sliding contact between the shortcircuited coil and the helical winding. As the sliding contact moves, the coil winding is gradually linearly cut into the circuit with the opening stroke. Only a small portion of a turn, for example, l/20th of a circuit, is commutated into the circuit as each individual contact on the ring sequentially engages a new'portion of the spiral winding. Thus, the incremental resistance and inductance change in the total series circuit is extremely small so that commutation can occur virtually arclessly. Moreover, all of the contact fingers will share the commutation duty equally.

As the coil is cut in, a repulsion force will be developed between the coil and the short-circuited ring where the coil and shoit-circuited ring are coaxial and concentric with one another. The electrical center of the ring, however, is axially displaced from the coil in a direction to produce a force in the direction needed to assist the opening operation.

This operation is of particular advantage in connection with a puffer type breaker where the force opposing the operating mechanism continually increases as the operating mechanism continues to reduce the volume between the cooperating piston and cylinder and increase the pressure within the cylinder to produce a gas blast through the separating contacts.

The novel electrodynamic system of the invention builds up an assist force which increases relatively uniformly in the opening stroke'since additional turns of the helical winding are inserted in the circuit as the interrupting operation continues and the contact stroke increases. It has been found that high speed operation is retained with the present invention, where, for example, the coil can be cut-in in less than 10 milliseconds and, after only a small portion of the total stroke of the interrupter has been executed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross-sectional view of a puffer type interrupter which uses the construction of the present invention and shows the contacts in their engaged position.

FIG. 1a is a circuit diagram of the interrupter of FIG. 1.

FIG. 2 is similar to FIG. 1 but shows the contacts in their open and disengaged position.

FIG. 3 is a cross-sectional view of FIG. 1 taken across the section line 33 in FIG. 1.

FIG. 4 is a cross-sectional view of FIG. 1 taken across the section line 44 in FIG. 1.

FIG. 5 is a cross-sectional view of FIG. 1 taken across the section line 5-5 in FIG. 1.

FIG. 6 is a lateral view of the coil of FIG. 1 without its insulation support to better illustrate the manner -in which the coil makes sliding contact with a cooperationg short-circuiting ring.

FIG. 7 is a front plan view of the short-circuited ring and its cooperating contacts in the interrupter of FIGS. 1 and 2.

FIG. 8 is a cross-sectional view of FIG. 7 taken across section line 88 in FIG. 7.

FIG. 9 is a cross-sectional view of a second embodiment of the invention and is a view similar to that of FIG. 1.

FIG. 9a is a circuit diagram of the embodiment of FIG. 9.

DETAILED DESCRIPTION OF THE DRAWINGS Referring first to FIGS. 1 and 2, there is illustrated an interrupter which consists of an outer insulation tube housing which has end caps 21 and 22 sealed thereto. The interior of housing 20 may be filled with a suitable dielectric gas, such as sulfur hexafluoride or mixtures of other gases with sulfur hexafiuoride which may be at any desired pressure, for example, from one to three atmospheres. End cap 21 has a stationary contact ring 23 extending therethrough and sealed thereto where the rod 23 serves as a stationary contact terminal 24 (FIG. la) for the stationary contact 25.

The stationary contact 25 is a conventional puffer interrupter contact and may consist of a plurality of segmented fingers or of any other desired configuration. The segmented nature of contact 25 is shown in FIG. 3 as having typical segmented contact finger sections 25a and 25b. These contact fingers are inwardly biased by suitable means to form high pressure contact with a cooperating movable contact 26 which is shown in its engaged and disengaged positions respectively with stationary contact 25 in FIGS. 1 and 2. The movable contact 26 is then fixed to an insulated operating rod 27 which is movable relative to the end cap 22 and through the sliding seal 28 in the end cap 22.

The movable contact 26 is also connected to a metallic cylinder 30 where the cylinder 30 may contain openings such as openings 31 and 32 in FIGS. 1 and 2 and the further openings 33 to 37, best shown in FIG. 4. Cylinder 30 serves as the cylinder of a puffer breaker, and openings 31 and 32 permit the passage of gas from the cylinder and through the separating contacts during operation of the interrupter. A slot 30a prevents the creation of a shorted turn in cylinder 30.

The passage of the gas through the various openings 30 to 37 is then suitably guided by an insulation nozzle 40 of conventional type and best shown in FIGS. 1, 2, 5, 7 and 8 which is fixed on cylinder 30. Nozzle 40 guides the gas created by the movement of cylinder 30 through arcs drawn between the separating contacts in order to most efficiently interrupt the arcs and deionize the gap between the opened contacts 25 and 26.

Cylinder 30 cooperates as shown in FIGS. 1, 2 and 5 with a stationary piston or ring 50. The piston 50, in accordance with the invention, is made of conductive material and thus serves as a short-circuited turn, the function of which will be later described. The stationary piston ring is fixed in position by the two conductive angle members 51 and (FIGS. 1, 2 and 5) wherein the angle 52 extends through housing 20 and serves as the terminal 53 for the movable contact 26. It will be further noted that a sliding ring (FIGS. 1 and 2) is provided between the insulated operating rod 27 and the ring 50.

In accordance with an important aspect of the invention, the interior surface of conductive cylinder 30 receives an insulation cylinder or coating and the insulation ring 70 then receives and physically supports an internal helical conductive winding 71 having a plural ity of turns. Winding 71 is illustrated to have four or five turns, but in actuality could contain any desired number of turns such as twenty turns. The internal surface of helical winding 71 is prepared to be exposed for sliding contact with the plurality of spaced contact members, such as contacts 'to 88 best shown in FIG. 7, wherein these contacts are disposed in a plane which is perpendicular to the axis of short-circuited ring 50 and to the axis of the helical winding 71. Thus, and as seen for example in FIG. 6, as the operating shaft 27 moves th'econtacts 80 to 88, ring 50 will sequentially sweep across the interior surface of coil 71, thereby to gradually insert the coils of winding 71 between th movable contact 26 and the tenninal 73.

It is now possible to understand the operation of the device of FIGS. 1 to 8, considering particularly the schematic circuit diagram of FIG. 1.1.

When the contacts 25 and 26 are closed, a direct circuit is formed which extends from terminal 24 through contact 23, stationary contact 25, movable contact 26, conductive cylinder 30 of FIGS. 1 and 2, through a rim of cylinder 30 which forms a contact 90, into the plurality of contacts 80 to 88 of ring 50 and then to the terminal 53. Thus the winding 71 is normally out of the main current circuit.

A suitable operating mechanism, such as operating mechanism of FIG. 1a, is provided to open the interrupter and is schematically shown in dotted lines as connected to both the movable contact 26 and coil 71 which are moved in the direction shown by the arrows to open the circuit. Thus, operating mechanism 95 moves rod 27 downwardly in FIG. 1 so that the interior surface of winding 71 rides over the contacts 80 to 88 of short-circuited ring 50, thereby gradually inserting turns of the winding between movable contact 26 and terminal 53. At the same time, gas is compressed between cylinder 30 and piston-short-circuited ring 50 so that gas will flow between the separating contacts 25 and 26.

When current is injected into the winding 71, the

magnetic field of the winding current will induce a circulating current in the short-circuited ring 50. The magnetic fields of the current in winding 71 and in ring 50 and will then create a strongly repulsive force between the active portion of winding 71 and the ring 50, thereby causing an additive force to the force of the operating mechanism 95, which tends to open the contacts. This additive force is of great value in assist ing the opening of the contacts since an opposing force is developed by the rapid increase in pressure within cylinder 30, as cylinder 30 moves downwardly and over the piston short-circuited winding 50 in FIG. 1 which opposes the opening force of operating mechanism 95. The additional repulsive force obtained by cutting in the winding 71 then provides supplemental force for opening the interrupter and, moreover, this operating force increases as the stroke of the operating mechanism 95 increases, thus applying and increasing the auxiliary force at the most desired time. Note further that at least some additive force is applied to the force of the operating mechanism 95 from the instant that the coil 71 begins to cut into the circuit.

In the embodiment of FIGS. 1 to 8, the coil 71 is relatively movable with respect to a relatively stationary short-circuiting coil 50. FIG. 9 and its accompanying circuit diagram FIG. 9a illustrate an arrangement in which the winding 71 is stationarily mounted.

In FIGS. 9 and 9a, components similar to those of FIGS. 1 to 8 have been given similar identifying numerals. The function of the short-circuited ring in FIGS. 9 and 9a is played by the short-circuited ring 101 which is a movable ring and which is mounted on the conductive cylinder 30. Note that, in both FIGS. 1 and 9 the conductive cylinder 30 is provided with a slot 30a (FIGS. 1, 2 and 4) which prevents the existence of a short-circuited turn in the cylinder 30.

In FIGS. 9 and 9a, the conductive piston 50 does not serve as a short-circuiting ring but simply serves as a puffer piston for the conductive cylinder 30 and as the member for making contact between terminal 53 and the conductive cylinder 30 when the cooperating contacts and 26 are closed. A segmented contact ring 102 is then carried on the interior of cylinder 30 and the segmented contact ring 102 serves the function of the contacts 80 to 88 of FIG. 7 for the embodiment of FIGS. 1 to 8. Thus, in the embodiment of FIG. 9, when the contacts are opened, the segmented contact ring 102 moves axially downward relative to the stationary winding 71, which is fixedly supported on the insulation ring 103. Turns of winding 71 are then gradually inserted in series with contact 26 and terminal 53. The portion of coil 71, which has been inserted, then tends to repel conductive ring 101 in a continuing downward direction in FIG.'9, thereby again adding the repulsive force which tends to assist the operating mechanism 95 to open the contacts 25 and 26. Note in FIG. 9a that the operating mechanism, as schematically illustrated by dotted lines, moves both contact 26 and short-circuited ring 101 (on the cylinder 30) at the same time while winding 71 is stationary.

Although this invention has been described with respect to the preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of this invention be limited, not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

l. A puffer circuit interrupter having an electromagnetic force assist operating means; said puffer circuit interrupter comprising first and second contacts movable between an engaged and disengaged position; first and second terminals for said first and second contacts respectively; a movable operating rod connected to at least said first contact for moving said contacts between their said engaged and disengaged positions; puffer means positioned adjacent said first and second contacts and including a relatively movable piston and cylinder connected to said operating rod and operated thereby to produce a blast of dielectric fluid through said contacts as said contacts move to their said disengaged position; a conductive winding fixed relative to one of said first and second contacts and having an axis substantially parallel to the direction of relative movement between said first and second contacts; a first cylindrical conductive contact ring fixed relative to the other of said first and second contacts and being coaxial with said winding; at least one peripheral surface of said winding and at least one peripheral surface of said first contact ring being exposed for sliding electrical contact with respect to one another, whereby said first Contact ring and said winding experience relative axial movement where said operating rod is operated; said first terminal being directly electrically connected to said first contact; said second terminal being directly connected to said first contact ring at least when said first and second contacts are in said engaged position;

one end of said winding being connected to said cylindrical contact ring, at least when said first and second contacts are in said engaged position; and a second contact ring fixed relative to said one of said first and second contacts and concentric with said first cylindrical contact ring and slidably engaging said first cylindrical contact ring when said first and second contacts are engaged; said second contact ring connected to said first contact at least when said first and second contacts are in said engaged position, whereby, when said first and second contacts are disengaged, said first cylindrical contact ring is continuously connected in series with increasing portions of said winding, and whereby circulating current is induced in said first contact ring, thereby to produce a repulsive electrodynamic force which tends to move said operating rod in the direction to disengage said first and second contacts.

2. The interrupter of claim 1 wherein said winding is fixed to said operating rod and is movable therewith, and wherein said first contact ring is fixed relative to said operating rod.

3. The interrupter of claim 2 wherein said winding is fixed to the interior periphery of said puffer cylinder, and wherein said second contact ring is fixed to the end of said puffer cylinder; said puffer cylinder being formed of conductive material and being electrically connected to said first contact.

4. The interrupter of claim 1 wherein said winding is fixed relative to said second contact, and wherein said second contact ring is fixed with said winding and wherein said first contact ring is fixed to said operating rod and is movable therewith.

5. The interrupter of claim 4 wherein said first contact ring is fixed to the end of said puffer cylinder; said puffer cylinder being formed of conductive mate rial and being connected to said first contact.

6. The interrupter of claim 1 wherein said operating rod is of insulation material.

7. The interrupter of claim 1 wherein said puffer cylinder has a nozzle orifice thereon for defining a dielectric fluid flow path between said first and second contacts when said contacts are opened.

8. A circuit interrupter having an electromagnetic force assist operating means; said circuit interrupter comprising first and second contacts movable between an engaged and disengaged position; first and second terminals for said first and second contacts respectively; a movable operating rod connected to at least said first contact for moving said contacts between their said engaged and disengaged positions; a conductive winding fixed relative to one of said first and second contacts and having an axis substantially parallel to the direction of relative movement between said first and second contacts; a first cylindrical conductive contact ring fixed relative to the other of said first and second contacts and being coaxial with said winding; at least one peripheral surface of said winding and at least one peripheral surface of said first contact ring being exposed for sliding electrical contact with respect to one another, whereby said first contact ring and said winding experience relative axial movement when said operating rod is operated; said first terminal being directly electrically connected to said first contact; said second terminal being directly connected to said first contact ring at least when said first and second contacts are in said engaged position; one end of said winding being connected to said cylindrical contact ring, at

least when said first and second contacts are in said engaged position; and a second contact ring fixed relative to said one of said first and second contacts and concentric with said first cylindrical contact ring and slidably engaging said first cylindrical contact ring when said first and second contacts are engaged; said second contact ring connected to said first contact at least when said first and second contacts are in said engaged position, whereby, when said first and second contacts are disengaged, said first cylindrical contact ring is continuously connected in series with increasing portions of said winding, and whereby circulating current is induced in said first contact ring, thereby to produce a repulsive electrodynamic force which tends to move said operating rod in the direction to disengage said first and second contacts.

9. The interrupter of claim 8 wherein said winding is fixed to said operating rod and is movable therewith, and wherein said first contact ring is fixed relative to said operating rod.

10. The interrupter of claim 8 wherein said winding is fixed relative to said second contact, and wherein said second contact ring is fixed with said winding, and wherein said first contact ring is fixed to said operating rod and is movable therewith.

11. An interrupter structure having an electrodynamically assisted operating mechanism comprising, in combination:

first and second relatively movable contacts movable between an engaged and disengaged position;

a conductive ring which defines a short-circuited turn;

a winding having a plurality of turns disposed coaxially with said conductive ring; said winding and said conductive ring being relatively axially movable;

a first terminal connected to said first contact and a second terminal connected to one end of said winding when said contacts are closed and to a second terminal;

and sliding contact means for slidably connecting said conductive ring to said winding, whereby relative axial movement between said conductive ring and said winding causes a change in the number of turns of said winding which are connected between said second contact and said second winding;

and operating means connected to said second contact and to at least one of said conductive ring or winding for moving said second contact to said disengaged position, and for simultaneously causing relative movement between said conductive ring and said winding to insert turns of said winding between said second contact and said second terminal.

12. The interrupter of claim 11 wherein said second contact and said winding are each connected to said operating means and are operated thereby.

13. The interrupter of claim 12 wherein said second contact and said conductive ring are each connected to said operating means and are operated thereby. 

1. A puffer circuit interrupter having an electromagnetic force assist operating means; said puffer circuit interrupter comprising first and second contacts movable between an engaged and disengaged position; first and second terminals for said first and second contacts respectively; a movable operating rod connected to at least said first contact for moving said contacts between their said engaged and disengaged positions; puffer means positioned adjacent said first and second contacts and including a relatively movable piston and cylinder connected to said operating rod and operated thereby to produce a blast of dielectric fluid through said contacts as said contacts move to their said disengaged position; a conductive winding fixed relative to one of said first and second contacts and having an axis substantially parallel to the direction of relative movement between said first and second contacts; a first cylindrical conductive contact ring fixed relative to the other of said first and second contacts and being coaxial with said winding; at least one peripheral surface of said winding and at least one peripheral surface of said first contact ring being exposed for sliding electrical contact with respect to one another, whereby said first contact ring and said winding experience relative axial movement where said operating rod is operated; said first terminal being directly electrically connected to said first contact; said second terminal being directly connected to said first contact ring at least when said first and second contacts are in said engaged position; one end of said winding being connected to said cylindrical contact ring, at least when said first and second contacts are in said engaged position; and a second contact ring fixed relative to said one of said first and second contacts and concentric with said first cylindrical contact ring and slidably engaging said first cylindrical contact ring when said first and second contacts are engaged; said second contact ring connected to said first contact at least when said first and second contacts are in said engaged position, whereby, when said first and second contacts are disengaged, said first cylindrical contact ring is continuously connected in series with increasing portions of said winding, and whereby circulating current is induced in said first contact ring, thereby to produce a repulsive electrodynamic force which tends to move said operating rod in the direction to disengage said first and second contacts.
 2. The interrupter of claim 1 wherein said winding is fixed to said operating rod and is movable therewith, and wherein said first contact ring is fixed relative to said operating rod.
 3. The interrupter of claim 2 wherein said winding is fixed to the interior periphery of said puffer cylinder, and wherein said second contact ring is fixed to the end of said puffer cylinder; said puffer cylinder being formed of conductive material and being electrically connected to said first contact.
 4. The interrupter of claim 1 wherein said winding is fixed relative to said second contact, and wherein said second contact ring is fixed with said winding and wherein said first contact ring is fixed to said operating rod and is movable therewith.
 5. The interrupter of claim 4 wherein said first contact ring is fixed to the end of said puffer cylinder; said pUffer cylinder being formed of conductive material and being connected to said first contact.
 6. The interrupter of claim 1 wherein said operating rod is of insulation material.
 7. The interrupter of claim 1 wherein said puffer cylinder has a nozzle orifice thereon for defining a dielectric fluid flow path between said first and second contacts when said contacts are opened.
 8. A circuit interrupter having an electromagnetic force assist operating means; said circuit interrupter comprising first and second contacts movable between an engaged and disengaged position; first and second terminals for said first and second contacts respectively; a movable operating rod connected to at least said first contact for moving said contacts between their said engaged and disengaged positions; a conductive winding fixed relative to one of said first and second contacts and having an axis substantially parallel to the direction of relative movement between said first and second contacts; a first cylindrical conductive contact ring fixed relative to the other of said first and second contacts and being coaxial with said winding; at least one peripheral surface of said winding and at least one peripheral surface of said first contact ring being exposed for sliding electrical contact with respect to one another, whereby said first contact ring and said winding experience relative axial movement when said operating rod is operated; said first terminal being directly electrically connected to said first contact; said second terminal being directly connected to said first contact ring at least when said first and second contacts are in said engaged position; one end of said winding being connected to said cylindrical contact ring, at least when said first and second contacts are in said engaged position; and a second contact ring fixed relative to said one of said first and second contacts and concentric with said first cylindrical contact ring and slidably engaging said first cylindrical contact ring when said first and second contacts are engaged; said second contact ring connected to said first contact at least when said first and second contacts are in said engaged position, whereby, when said first and second contacts are disengaged, said first cylindrical contact ring is continuously connected in series with increasing portions of said winding, and whereby circulating current is induced in said first contact ring, thereby to produce a repulsive electrodynamic force which tends to move said operating rod in the direction to disengage said first and second contacts.
 9. The interrupter of claim 8 wherein said winding is fixed to said operating rod and is movable therewith, and wherein said first contact ring is fixed relative to said operating rod.
 10. The interrupter of claim 8 wherein said winding is fixed relative to said second contact, and wherein said second contact ring is fixed with said winding, and wherein said first contact ring is fixed to said operating rod and is movable therewith.
 11. An interrupter structure having an electrodynamically assisted operating mechanism comprising, in combination: first and second relatively movable contacts movable between an engaged and disengaged position; a conductive ring which defines a short-circuited turn; a winding having a plurality of turns disposed coaxially with said conductive ring; said winding and said conductive ring being relatively axially movable; a first terminal connected to said first contact and a second terminal connected to one end of said winding when said contacts are closed and to a second terminal; and sliding contact means for slidably connecting said conductive ring to said winding, whereby relative axial movement between said conductive ring and said winding causes a change in the number of turns of said winding which are connected between said second contact and said second winding; and operating means connected to said second contact and to at least one of said condUctive ring or winding for moving said second contact to said disengaged position, and for simultaneously causing relative movement between said conductive ring and said winding to insert turns of said winding between said second contact and said second terminal.
 12. The interrupter of claim 11 wherein said second contact and said winding are each connected to said operating means and are operated thereby.
 13. The interrupter of claim 12 wherein said second contact and said conductive ring are each connected to said operating means and are operated thereby. 